1. Field of the Invention
This invention relates in general to impact tools and in particular to an improved motorized impact tool using a spring and cam to cause reciprocating impacts.
2. Description of the Prior Art
Cam and spring impact tools normally include a driving shaft rotated by a motor, a hammer mounted for reciprocation, and a cam and roller assembly for translating rotational motion to reciprocation. A spring urges the hammer in one direction to create the impact. The cam is annular with a double inclined camming surface. A pair of cam rollers are rotated, the rise and fall causing the reciprocation of the hammer.
Because of inaccuracies in machining the camming surface and the connection of the rollers to the driving shaft, inequalities of the load of the cam rollers on the camming surface may result, causing wear and breakage. In U.S. Pat. 3,302,732, the transverse axle on which the cam rollers are mounted is slightly larger in the center than at the ends. This allows the rollers to tip slightly about the axis to equalize the load. While this barrel shaped axle performs satisfactorily, machining cost are expensive.